Cover Page
Jan. 21, 2021
Jan. 20, 2021
Oct. 21, 2020
Entity Information [Line Items]      
Document Type   8-K  
Document Period End Date Jan. 21, 2021    
Entity Registrant Name   KeyCorp  
Entity Incorporation, State or Country Code OH    
Entity File Number 001-11302    
Entity Tax Identification Number   34-6542451  
Entity Address, Address Line One     127 Public Square,
Entity Address, City or Town     Cleveland,
Entity Address, State or Province     OH
Entity Address, Postal Zip Code   44114-1306  
City Area Code   216  
Local Phone Number   689-3000  
Written Communications   false  
Soliciting Material   false  
Pre-commencement Tender Offer   false  
Pre-commencement Issuer Tender Offer   false  
Entity Emerging Growth Company   false  
Amendment Flag   false  
Entity Central Index Key   0000091576  
Common Stock      
Entity Information [Line Items]      
Title of 12(b) Security   Common Shares, $1 par value  
Trading Symbol   KEY  
Security Exchange Name   NYSE  
Series E Preferred Stock      
Entity Information [Line Items]      
Title of 12(b) Security   Depositary Shares (each representing a 1/40th interest in a share of Fixed-to-Floating Rate Perpetual Non-Cumulative Preferred Stock, Series E)  
Trading Symbol   KEY PrI  
Security Exchange Name   NYSE  
Series F Preferred Stock      
Entity Information [Line Items]      
Title of 12(b) Security   Depositary Shares (each representing a 1/40th interest in a share of Fixed Rate Perpetual Non-Cumulative Preferred Stock, Series F)  
Trading Symbol   KEY PrJ  
Security Exchange Name   NYSE  
Series G Preferred Stock      
Entity Information [Line Items]      
Title of 12(b) Security   Depositary Shares (each representing a 1/40th interest in a share of Fixed Rate Perpetual Non-Cumulative Preferred Stock, Series G)  
Trading Symbol   KEY PrK  
Security Exchange Name   NYSE